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package org.openjdk.jmh.samples;


import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

import org.openjdk.jmh.annotations.Mode;

import org.openjdk.jmh.annotations.OutputTimeUnit;

import org.openjdk.jmh.runner.Runner;

import org.openjdk.jmh.runner.RunnerException;

import org.openjdk.jmh.runner.options.Options;

import org.openjdk.jmh.runner.options.OptionsBuilder;


import java.util.concurrent.TimeUnit;


public class JMHSample_02_BenchmarkModes {


 /*

  * JMH generates lots of synthetic code for the benchmarks for you during

  * the benchmark compilation. JMH can measure the benchmark methods in lots

  * of modes. Users may select the default benchmark mode with a special

  * annotation, or select/override the mode via the runtime options.

  *

  * With this scenario, we start to measure something useful. Note that our

  * payload code potentially throws exceptions, and we can just declare them

  * to be thrown. If the code throws the actual exception, the benchmark

  * execution will stop with an error.

  *

  * When you are puzzled with some particular behavior, it usually helps to

  * look into the generated code. You might see the code is doing not

  * something you intend it to do. Good experiments always follow up on the

  * experimental setup, and cross-checking the generated code is an important

  * part of that follow up.

  *

  * The generated code for this particular sample is somewhere at

  * target/generated-sources/annotations/.../JMHSample_02_BenchmarkModes.java

  */


 /*

  * Mode.Throughput, as stated in its Javadoc, measures the raw throughput by

  * continuously calling the benchmark method in a time-bound iteration, and

  * counting how many times we executed the method.

  *

  * We are using the special annotation to select the units to measure in,

  * although you can use the default.

  */


 @Benchmark

 @BenchmarkMode(Mode.Throughput)

 @OutputTimeUnit(TimeUnit.SECONDS)

 public void measureThroughput() throws InterruptedException {

  TimeUnit.MILLISECONDS.sleep(100);

 }


 /*

  * Mode.AverageTime measures the average execution time, and it does it

  * in the way similar to Mode.Throughput.

  *

  * Some might say it is the reciprocal throughput, and it really is.

  * There are workloads where measuring times is more convenient though.

  */


 @Benchmark

 @BenchmarkMode(Mode.AverageTime)

 @OutputTimeUnit(TimeUnit.MICROSECONDS)

 public void measureAvgTime() throws InterruptedException {

  TimeUnit.MILLISECONDS.sleep(100);

 }


 /*

  * Mode.SampleTime samples the execution time. With this mode, we are

  * still running the method in a time-bound iteration, but instead of

  * measuring the total time, we measure the time spent in *some* of

  * the benchmark method calls.

  *

  * This allows us to infer the distributions, percentiles, etc.

  *

  * JMH also tries to auto-adjust sampling frequency: if the method

  * is long enough, you will end up capturing all the samples.

  */

 @Benchmark

 @BenchmarkMode(Mode.SampleTime)

 @OutputTimeUnit(TimeUnit.MICROSECONDS)

 public void measureSamples() throws InterruptedException {

  TimeUnit.MILLISECONDS.sleep(100);

 }


 /*

  * Mode.SingleShotTime measures the single method invocation time. As the Javadoc

  * suggests, we do only the single benchmark method invocation. The iteration

  * time is meaningless in this mode: as soon as benchmark method stops, the

  * iteration is over.

  *

  * This mode is useful to do cold startup tests, when you specifically

  * do not want to call the benchmark method continuously.

  */

 @Benchmark

 @BenchmarkMode(Mode.SingleShotTime)

 @OutputTimeUnit(TimeUnit.MICROSECONDS)

 public void measureSingleShot() throws InterruptedException {

  TimeUnit.MILLISECONDS.sleep(100);

 }


 /*

  * We can also ask for multiple benchmark modes at once. All the tests

  * above can be replaced with just a single test like this:

  */

 @Benchmark

 @BenchmarkMode({Mode.Throughput, Mode.AverageTime, Mode.SampleTime, Mode.SingleShotTime})

 @OutputTimeUnit(TimeUnit.MICROSECONDS)

 public void measureMultiple() throws InterruptedException {

  TimeUnit.MILLISECONDS.sleep(100);

 }


 /*

  * Or even...

  */


 @Benchmark

 @BenchmarkMode(Mode.All)

 @OutputTimeUnit(TimeUnit.MICROSECONDS)

 public void measureAll() throws InterruptedException {

  TimeUnit.MILLISECONDS.sleep(100);

 }


 /*

  * ============================== HOW TO RUN THIS TEST: ====================================

  *

  * You are expected to see the different run modes for the same benchmark.

  * Note the units are different, scores are consistent with each other.

  *

  * You can run this test:

  *

  * a) Via the command line:

  *    $ mvn clean install

  *    $ java -jar target/benchmarks.jar JMHSample_02 -f 1

  *    (we requested a single fork; there are also other options, see -h)

  *

  * b) Via the Java API:

  *    (see the JMH homepage for possible caveats when running from IDE:

  *      http://openjdk.java.net/projects/code-tools/jmh/)

  */


 public static void main(String[] args) throws RunnerException {

  Options opt = new OptionsBuilder()

          .include(JMHSample_02_BenchmarkModes.class.getSimpleName())

          .forks(1)

          .build();


  new Runner(opt).run();

 }
//本例介绍了注解 @OutputTimeUnit 和 @BenchmarkMode。
// @OutputTimeUnit 可以指定输出的时间单位，可以传入 java.util.concurrent.TimeUnit 中的时间单位，最小可以到纳秒级别；
// @BenchmarkMode 指明了基准测试的模式
// Mode.Throughput ：吞吐量，单位时间内执行的次数
// Mode.AverageTime：平均时间，一次执行需要的单位时间，其实是吞吐量的倒数
// Mode.SampleTime：是基于采样的执行时间，采样频率由JMH自动控制，同时结果中也会统计出p90、p95的时间
// Mode.SingleShotTime：单次执行时间，只执行一次，可用于冷启动的测试
}